The present invention relates to a cutting tool for turning operations. More specifically, the invention relates to a cutting tool for a bar peeling operation performed on solid or hollow bars formed of stainless steel or other heat resist materials. The cutting tool comprises a holder equipped with one or several inserts of a polygonal form including an upper chip face, an opposite bottom face and a clearance face located therebetween, whereby the intersection of the chip face and the clearance face forms a cutting edge.
Bar peeling as a metalworking operation means that a non-rotatable bar is axially displaced through a central hole of a rotary cutter head. The cutter head is provided with several tools which remove from the bar a thin layer of millscale, surface cracks, etc., that results from the hot rolling of such bars or tubes. In order to achieve the best results regarding tolerances and surface finish, two different types of inserts, i.e., roughing and finishing inserts, are usually combined in the same holder. One of the most commonly used inserts for bar peeling is a so-called trigonal inserts as shown and described in U.S. Pat. No. 4,035,888. That insert is in the form of a regular polygonal body the corners of which are configured symmetrically about a corner bisector. Such inserts, however, have somewhat limited utility because they do not enable desired results to be achieved when large feeds are involved.
In view thereof, it is a purpose of this invention to provide a new type of cutting tool with an insert having continuously convexly curved cutting edge portions, to be used together with subsequent wiper inserts at large cutting depths.
It is another purpose of the invention to provide an insert with an extended lifetime.
It is yet another purpose of the invention to provide an insert which allows favorable chipbreakers thereon to be used for both large and small cutting depths at large feeds. It is yet another purpose of the invention to provide an insert having a short contact surface towards the workpiece which can reduce the tendency for vibrations to occur during a cutting operation.